1. Field of the Invention
This invention relates to block tongs and more particularly to a multi-unit block tong assembly which may be used to lift and transport large building blocks such as those used in retaining walls, steps, etc.
2. Description of the Related Art
Brick tongs have been used for many years to enable a workman to carry a plurality of bricks from a source of supply to a work site. The conventional brick tongs comprise plates or hooks disposed at ends of a pair of pivoting arms designed so that when the tongs are lifted, the plates or hooks are moved into engagement with the ends of the outermost bricks so that the bricks are firmly grasped to enable the bricks to be lifted and carried. During the past several years, large concrete blocks have been fabricated for use in retaining walls, steps, etc. The blocks are quite large and heavy and are difficult for a workman to move from a pallet or the like to the job site.
In the past, applicant devised a multi-unit concrete block tong assembly wherein the block tongs could lift and carry a plurality of concrete blocks from a pallet to the job site with the block tongs being supported from the end of a boom mounted on a skid-steer loader or the like. Although the block tongs of applicant""s previous device did perform satisfactorily, the previous device required the presence of a worker to permit the block tongs to be selectively locked into the open position so that the tongs could be mounted on the concrete blocks and so that the block tongs could be removed from the concrete blocks once the blocks were properly positioned adjacent the job site. In the device described in applicant""s co-pending application, applicant provided a means whereby the block tongs could be remotely selectively locked into the open position. Although the device of the co-pending application works extremely well, the device thereof did not have any means for manually overriding the electric solenoids thereof. The manual override feature has been found to be important in those situations wherein the supporting vehicle did not have the capability of electrically operating the electric solenoids or in those situations wherein the electric wires supplying power to the solenoids were inadvertently severed or damaged.
A multi-unit concrete block tong assembly is provided which includes three top support members pivotally operatively connected at one end thereof to one end of three bottom support members. A front plate is secured to one end of each of the top support members for movement therewith. A back plate is longitudinally adjustably secured to each of the bottom support members adjacent the other end thereof. A lifting apparatus is operatively connected to the three top support members whereupon upward movement of the three top support members by the lifting device will cause the top support members to pivot with respect to the bottom support members. A solenoid operated locking bolt is selectively movably mounted within each of the top support members and is movable between extended and retracted positions. The solenoid is operatively connected to each of the locking bolts for moving the dead bolt from its extended position to its retracted position. An upstanding support is provided on each of the bottom support members which extends upwardly into the associated top support member and which is adapted to receive the locking bolt of the associated top support member to lock the assembly in its open position. When the solenoids are activated, the locking bolts are retracted from engagement with the supports so that when the lifting device raises the assembly, the top support members pivot with respect to the bottom support members to urge the front plates and back plates of the assembly into frictional engagement with the ends of the concrete blocks. A manual spring-loaded override is provided for manually moving each of the dead bolts to their retracted positions and to maintain the dead bolts in the retracted position by a locking mechanism. When the locking mechanisms are disengaged, the dead bolts return to their extended positions.
It is therefore a principal object of the invention to provide an improved multi-unit concrete block tong assembly.
A further object of the invention is to provide a multi-unit concrete block tong assembly which includes a solenoid operated dead bolt designed to lock the assembly in its open position, thereby eliminating the need for the presence of a worker.
A further object of the invention is to provide a concrete block tong assembly which is designed to lift and carry a plurality of concrete blocks.
A further object of the invention is to provide a concrete block tong assembly including means for rotating the same to properly position the assembly with respect to the concrete blocks to be lifted and carried and to permit the concrete blocks to be properly positioned within or at the job site.
A further object of the invention is to provide a multi-unit concrete block tong assembly which includes a solenoid operated dead bolt designed to lock the assembly in its open position and further including a spring-loaded manual override.
A further object of the invention is to provide a multi-unit concrete block tong assembly which includes a solenoid operated dead bolt designed to lock the assembly in its open position and further including a spring-loaded manual override and which further includes means for maintaining each of the dead bolts in their retracted positions when the manual overrides are employed.
These and other objects will be apparent to those skilled in the art.